This invention relates to ultraviolet (UV) light sources, and more particularly to the prevention or control of the formation of ozone from such sources.
The invention is particularly adapted, among other possible uses, for use with spectrophotometers, for example. Many biological, physiological, or chemical phenomena are analyzed by passing light through solutions, suspensions, or other liquid samples and detecting the reflection or transmission characteristics thereof. Such spectrophotometers include a high energy source which may, for example, be a deuterium or xenon arc lamp for providing light throughout a wavelength range approximately 190-360 nanometers (nm.).
It is known that oxygen absorbs ultraviolet (UV) emission in the wavelength range below approximately 200 nm. This absorption causes a change of state to ozone, and thus at the window of an UV source in an air environment ozone is generated. Ozone absorbs at wavelength bands of about 254 nm. and at about 600 nm. It will be appreciated that the generation of ozone in the optical path of a spectrophotometer changes the energy throughput of the instrument, which is normally a noisy process. These instruments are very delicate in nature and, hence, any variation in energy throughput is a significant factor in the overall performance of the instrument. Moreover, various governmental agencies issue regulations for ozone emission which must be complied with.
Heretofore, attempts have been made to overcome this problem by the provision of exhaust fans, hoods, deozonators, and the like. However, such devices have not been entirely successful and, accordingly, it is an object of the present invention to overcome or to reduce to insignificance this problem in a new and improved manner, as will become apparent as the description proceeds.